Acknowledgment: The authors thank Barbra Rabson and Jan Singer of Massachusetts Health Quality Partners, who facilitated access to the data sets used in this study.

Grant Support: By a contract from the U.S. Department of Labor (J-9-P-2-0033); a career development award (KL2 RR024154) from the National Center for Research Resources, a component of the National Institutes of Health (Dr. Mehrotra); and grant 60517 from the Robert Wood Johnson Foundation's Health Care Financing and Organization program (Dr. Thomas).

Reproducible Research Statement:Study protocol and statistical code: Available from Dr. Mehrotra (mehrotra@rand.org). Data set: Available through written agreements with the authors, Massachusetts Health Quality Partners, and the health plans that provided the data.

The full content of Annals is available to subscribers

Health plan administrators and government payers use cost profiles of individual physicians, which compare a physician with his or her peers in terms of expenditures incurred, for various applications, including physician “report cards” and the categorizing of physicians into tiered products (1). These applications are intended to generate incentives for physicians to decrease health care costs. However, medical societies (2) and a state attorney general (3–5) have questioned the methods used to create cost profiles.